1. Field of the Invention
This invention relates generally to information retrieval systems, and, more particularly, to information retrieval systems that direct users to objects containing information (e.g., images, text, and/or sounds).
2. Description of the Related Art
Information retrieval (IR) may be generally described as the study of systems for indexing, storing, searching, and retrieving data relevant to a human user""s need for information. Indexing is the process of converting data within a collection of objects (e.g., documents) into a form suitable for easy search and retrieval. The goal of information retrieval (IR) systems is to direct the user to those objects in the collection that will best satisfy the user""s need for information.
Almost all information retrieval (IR) systems today accept either Boolean text search queries, or text pattern search queries. Boolean text search queries typically include Boolean combinations of words (e.g., xe2x80x9cinformation AND retrieval,xe2x80x9d xe2x80x9cvision OR sight,xe2x80x9d xe2x80x9cpython AND (NOT monty)xe2x80x9d). Text pattern search queries typically include word strings or phrases (e.g., xe2x80x9cgreat barrier reef,xe2x80x9d as opposed to the Boolean expression xe2x80x9cgreat AND barrier AND reefxe2x80x9d).
A problem arises in that information retrieval (IR) systems typically rely upon measurements of similarity between objects in a collection during indexing, and between queries and stored data during data retrieval. Words and phrases, used by almost all information retrieval (IR) systems today, may be thought of as being xe2x80x9chighly granular.xe2x80x9d The resulting xe2x80x9cfine granularityxe2x80x9d leads to mistakes in the recognition of degrees of similarity among objects during indexing, and between queries and objects during data retrieval. These errors are foreign to human perception that easily shifts the logical frame of reference to compensate for variation of granularity in the similarity recognition task among objects.
For example, if a human subject were to visually scan two different areas of, for example, a beach, the subject would have little difficulty in recognizing both areas as belonging to the same general class of xe2x80x9cBeach.xe2x80x9d However, if a machine (e.g., a computer) were to consider only grains of sand from the two different areas of the beach, the machine might conclude that, due to differences in, for example, the size, texture, and/or coarseness of the grains of sand, the two areas do not in fact belong to the same general class of Beach.
Computers employed in information retrieval (IR) systems today make similar mistakes when attempting to determine degrees of similarity among objects during indexing, and between queries and objects during data retrieval. As a result, information retrieval (IR) systems are not always highly effective when retrieving data deemed relevant to a human user""s need for information.
Known efforts to reduce the granularity problem inherent when using words and phrases for similarity measurement include statistical techniques such as latent semantic indexing (LSI) and singular value decomposition (SVD). In general, such techniques result in a smaller pool of words or phrases upon which to measure similarity among objects during indexing, and between queries and objects during data retrieval.
The Internet is a global network connecting millions of computers worldwide. In 1999, the Internet had over 200 million users in over 100 different countries. The World Wide Web (abbreviated WWW, and often referred to simply as xe2x80x9cthe Webxe2x80x9d) is a portion of the Internet servers supporting documents formatted according to the hypertext markup language (HTML). The hypertext markup language (HTML) supports links to graphics, audio, and video files, as well as links to other HTML documents (i.e. xe2x80x9chyperlinksxe2x80x9d). Computer programs called xe2x80x9cWeb browsersxe2x80x9d are commonly used to access HTML documents on the World Wide Web.
For example, assume an HTML document has a link to graphics, audio, and/or video files, as well as a links to other HTML documents. When a computer user accesses the HTML document, the graphics, audio, and/or video files may be displayed on the user""s computer. The user may transition from the HTML document to another HTML document simply by clicking on the link to the other HTML document.
The number of HTML documents accessible today via the Web may exceed one billion. xe2x80x9cSearch enginesxe2x80x9d are available to aid users in accessing specific HTML documents in this large number of HTML documents. A search engine is a computer program that accepts a user query including words called xe2x80x9ckeywords,xe2x80x9d searches indexed HTML documents for the keywords, and returns a list of the indexed HTML documents including the keywords. The list typically includes hyperlinks to the corresponding HTML documents.
Despite careful design, search engines often return lists containing a large number of xe2x80x9cjunk resultsxe2x80x9d along with a small number of xe2x80x9cmeaningful resultsxe2x80x9d a user is interested in. Being more plentiful than the meaningful results, the junk results often obscure the meaningful results. As most users are only willing to look at the first few tens of results, the user may never discover highly relevant HTML documents in a list containing hundreds of results.
As the number of HTML documents available on the Web continues to grow, new information retrieval techniques are needed that will allow search engines to return greater numbers of xe2x80x9cmeaningful resultsxe2x80x9d and/or smaller numbers of xe2x80x9cjunk results.xe2x80x9d
The present invention is directed to methods that may solve, or at least reduce, some or all of the aforementioned problems, and systems incorporating the method.
A method is described that may be used to generate numerical values indicative of frequencies of selected features in one or more objects. The method includes arranging columns of a matrix in sum total order, wherein the matrix has one or more rows, and multiple intersecting columns. Each of the rows of the matrix represents a different object, and each of the columns represents a different one of multiple selected features. Values reside at row-column intersections. A given value residing at an intersection of a given row and a given column corresponds to the given row and the given column, and represents the frequency of the selected feature represented by the given column in the object represented by the given row.
The matrix is converted to a binary matrix (e.g., comprising binary values xe2x80x980xe2x80x99 and xe2x80x981xe2x80x99). The columns of the matrix are divided into multiple segments of equal length. The matrix columns encompassed by each segment are replaced by a single column. Values at intersections of the rows and the single columns are set equal to numerical values indicative of ratios of a total number of one of the binary values (e.g., a total number of xe2x80x981xe2x80x99s) in a portion of the corresponding row encompassed by a segment to a total number of the one of the binary values (e.g. a total number of xe2x80x981xe2x80x99s) in the corresponding row.
A computer system embodying the method is also described, as is a carrier medium including program instructions for carrying out the method. The carrier medium may be, for example, a computer-readable storage medium such as a floppy disk or a compact disk read only memory (CD-ROM) disk.